> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hightouch.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Data activation concepts

> Learn the foundational concepts in Hightouch—sources, models, schema, syncs, destinations, and change data capture—that power Reverse ETL and the Composable CDP.

## Overview

Data activation is the process of moving trusted warehouse data into the tools where teams take action — ad platforms, CRMs, marketing automation, support desks, and more. Hightouch calls this process **Reverse ETL**.

This page covers the building blocks that make Reverse ETL work: **sources**, **models**, **schema**, **syncs**, **destinations**, and **change data capture**. It is written for data teams and engineers who set up these components, but it also helps marketers understand the concepts they encounter in Customer Studio.

> [!NOTE]
>
> [**Explore the interactive architecture diagram**](https://architecture.hightouch.com/?from=docs\&product=reverse-etl\&utm_source=hightouch-docs\&utm_medium=referral\&utm_campaign=architecture-explorer\&utm_content=reverse-etl)
>
> See how data flows and where Reverse ETL fits in your stack.

## Sources

![Sources diagram](https://mintcdn.com/hightouch-3c037897/L_vQfA0JQEpeGUUo/images/get-started/source-diagram.png?fit=max\&auto=format\&n=L_vQfA0JQEpeGUUo\&q=85\&s=ec0fb2e7ce29a1364429623ab0771f3f)

A **source** is any system where your data resides. Common examples include Snowflake, BigQuery, Databricks, and PostgreSQL. Sources can also be files, APIs, or BI tools. In practice, this is where customer and business data lives — purchase history, campaign activity, product usage, and so on.

See [Sources overview](https://docs.hightouch.com/sources/overview.md) for setup instructions and a full list of supported connectors.

## Models

![Models diagram](https://mintcdn.com/hightouch-3c037897/L_vQfA0JQEpeGUUo/images/get-started/models-diagram-text.png?fit=max\&auto=format\&n=L_vQfA0JQEpeGUUo\&q=85\&s=d80cf91f317cd6b9bf14bdb11560615e)

A [**model**](https://docs.hightouch.com/models/creating-models.md) defines what data to query from a source. Models can represent users, events, products, or any other entity. Data teams typically create models by writing SQL in the editor, selecting from tables or views, or re-using dbt models and BI queries from Looker or Sigma.

![Select a modeling method](https://mintcdn.com/hightouch-3c037897/L_vQfA0JQEpeGUUo/images/get-started/select-a-model-method.png?fit=max\&auto=format\&n=L_vQfA0JQEpeGUUo\&q=85\&s=aced58435831199d35c6b01cfd6e525f)

Every model requires a **unique primary key** to identify each row and track changes between syncs. In practice, a model is a reusable dataset — “all active customers,” “abandoned carts,” or “email subscribers” — that can power multiple syncs and audiences.

See [Models overview](https://docs.hightouch.com/models/creating-models.md) for details on each modeling method.

## Schema

![Schema diagram](https://mintcdn.com/hightouch-3c037897/L_vQfA0JQEpeGUUo/images/get-started/schema-diagram.png?fit=max\&auto=format\&n=L_vQfA0JQEpeGUUo\&q=85\&s=ad481795db60716b5286fea75e0928cf)

A **schema** is a one-time configuration that connects your models to [Customer Studio](https://docs.hightouch.com/customer-studio/overview.md). Data teams define a parent model (typically users), then add related models, events, and relationships. Once the schema is configured, marketers can build [audiences](https://docs.hightouch.com/customer-studio/usage.md) and [journeys](https://docs.hightouch.com/customer-studio/journeys.md) in a no-code UI. Audiences cannot be created until this step is complete.

In Customer Studio, the schema determines which fields, events, and relationships appear in the audience builder — it is how marketers access model data without writing SQL.

See [Customer Studio schema setup](https://docs.hightouch.com/customer-studio/schema.md) for configuration steps.

## Syncs

![Syncs diagram](https://mintcdn.com/hightouch-3c037897/L_vQfA0JQEpeGUUo/images/get-started/syncs-diagram-text.png?fit=max\&auto=format\&n=L_vQfA0JQEpeGUUo\&q=85\&s=cc08572e3e0c70af6b87d1f14a9e0733)

A [**sync**](https://docs.hightouch.com/syncs/overview.md) defines how data appears in the destination and when. Syncs specify:

* **Type**: object, event, audience, etc.
* **Mode**: insert, update, upsert, or archive
* **Mapping**: how source columns map to destination fields
* **Schedule**: interval, cron, or triggered by tools like dbt Cloud or Airflow

Multiple syncs can be created from the same model to support different use cases. In practice, a sync is how a dataset shows up in tools like Braze, Salesforce, or Meta Ads so teams can act on it.

See [Syncs overview](https://docs.hightouch.com/syncs/overview.md) for configuration details and scheduling options.

## Destinations

![Destinations diagram](https://mintcdn.com/hightouch-3c037897/L_vQfA0JQEpeGUUo/images/get-started/destination-diagram.png?fit=max\&auto=format\&n=L_vQfA0JQEpeGUUo\&q=85\&s=ce1dbb04aa2e6feea220a433ffa40a0c)

A **destination** is any system where data is consumed — CRMs, ad platforms, support tools, analytics, or custom APIs. These are the tools where teams build campaigns, measure results, and engage with customers.

See [Destinations overview](https://docs.hightouch.com/destinations/overview.md) for a full list of supported destinations.

## Change data capture (CDC)

Hightouch optimizes syncs with **change data capture (CDC)**. Instead of sending the full query result on every run, CDC compares the current results to the previous run and only sends new, changed, and removed rows. This keeps downstream tools current without redundant updates.

![Basic vs Lightning sync](https://mintcdn.com/hightouch-3c037897/L_vQfA0JQEpeGUUo/images/get-started/cdc-diagram.png?fit=max\&auto=format\&n=L_vQfA0JQEpeGUUo\&q=85\&s=fa2c871136b2a9ff88ee9e374285b0f8)

By default, CDC runs on Hightouch-managed infrastructure. For higher performance at scale, you can enable the [Lightning sync engine](https://docs.hightouch.com/syncs/lightning-sync-engine.md) to compute CDC directly in the warehouse.

> [!TIP]
>
> Hightouch recommends enabling the [Lightning sync engine](https://docs.hightouch.com/syncs/lightning-sync-engine.md) during source setup. Beyond performance, it’s required for features like [Journeys](https://docs.hightouch.com/customer-studio/journeys.md), [Sampling](https://docs.hightouch.com/customer-studio/sampling.md), [Warehouse Sync Logs](https://docs.hightouch.com/syncs/warehouse-sync-logs.md), [Audience Snapshots](https://docs.hightouch.com/customer-studio/audience-snapshots.md), and [Identity Resolution](https://hightouch.com/platform/identity-resolution). See the [full list of requirements](https://docs.hightouch.com/syncs/lightning-sync-engine.md#when-the-lightning-sync-engine-is-required).

See [Change data capture overview](https://docs.hightouch.com/syncs/cdc.md) for details on how diffing works and how to choose a sync engine.

## How it fits together

1. Connect a **source** (e.g., Snowflake)
2. Define **models** that query the data you need (e.g., “active customers in the last 30 days”)
3. Configure the **schema** so marketers can access model data in Customer Studio
4. Set up **destinations** and **syncs** to deliver data to downstream tools

From there, marketers build [audiences](https://docs.hightouch.com/customer-studio/usage.md), coordinate [journeys](https://docs.hightouch.com/customer-studio/journeys.md), run [experiments](https://docs.hightouch.com/customer-studio/experiments.md), and measure results — all from warehouse data, without writing SQL.

These primitives are the foundation for Hightouch's marketing tools. For a walkthrough of the marketing workflow — audiences, agents, journeys, AI Decisioning, and measurement — see [Daily usage for marketers](https://docs.hightouch.com/getting-started/business.md).

## Next steps

> [!TIP]
>
> **Data teams**: Get started with the [Quick start guide](https://docs.hightouch.com/getting-started/data.md).

* Set up your first [source](https://docs.hightouch.com/sources/overview.md)
* Create a [model](https://docs.hightouch.com/models/creating-models.md)
* Configure a [sync](https://docs.hightouch.com/syncs/overview.md)
* Explore [destinations](https://docs.hightouch.com/destinations/overview.md)
* See the marketing workflow in [Daily usage for marketers](https://docs.hightouch.com/getting-started/business.md)